We have a Captiva and have both a Maxirider and another Safe N Sound reversible (both forward facing) seats in at the moment, TBH I have no idea how we would fit a third seat in as there's not much room left. And the ambo guy who installed the bub capsule way back when DS2 was a newborn reckoned the middle seat belt in the Captiva was off-centre and therefore not suited to 3 seats. Just one opinion though I guess. I just figure that if I have to put a third car seat in the back we'd have to find slim-line seats.
Totally, you do need slimmer seats... Has anyone tried the infa vario booster seat....3cm skinnier than the safe n sound hi-liner and maximum safety rating with a harness (harness is also recommended on safe n sound) .. they are $70 off at babies direct at the moment....I got 2, one for each car....will make total 6 inches diff with 2 boosters in the back eventually.... that's huge ... the lovely girl went and measured them on the floor for me...